Stencil pad tensioning means in a duplicating device



March 15, 1966 M. J. DOPPELT 3,240,149

STENCIL PAD TENSIONING MEANS IN A DUPLICATING DEVICE Filed Nov. 26, 1965 INVENTOR.

MAX J- DOPPELT F165 UM C m ATTORNEY United States Patent 3,240,149 STENCIL PAD TENSEONING MEANS IN A DUPLICATING DEVHIE Max It. Doppelt, 1920 W. Snnnyside Ave, Chicago, Ill. Filed Nov. 26, 1963, Ser. No. 326,073 2 Claims. (Cl. 101125) This invention relates to improvements in duplicating devices, and more particularly to an improvement in a small inexpensive duplicating device that is provided with a stencil and is capable of making a large number of copies with the stencil.

In my US. Patent No. 2,203,192, there was disclosed a duplicating device which was portable, inexpensive and yet efficient, and it could be used for making a large number of copies from a stencil.

The duplicating device after many years of use has been found inadequate in certain respects. One disadvan tage thereof has to do with the means holding the muslin wrapper tautly against the arcuate portion of the printing platen. The disadvantage with the manner in which the muslin was held was that the muslin was not pulled firmly against the arcuate portion with the same amount of force on all parts of each end of the muslin and accordingly the muslin was unevenly pulled against the arcuate printing portion of the platen thus resulting in unclear printing at times.

I have provided an improved means of causing the muslin to be held firmly against the arcuate platen portion with an even amount of force being exerted at all points where there is force pulling the muslin. I use a movable bar that is associated with the muslin at one end and it has a pair of thumb nuts that are threadedly fast ened at each end of the movable bar. The other end of the muslin is anchored to a lock bar which is removably fastened to the printing platen. The lock bar and movable bar are associated with the printing platen on each side of the arcuate surface thereof and hold the muslin wrapper firmly against the platen. The thumb nuts are each associated with a cam surface and when they are each turned in a certain direction an equal distance they cause the movable bar to pull the muslin taut with equal force at each end of the muslin thereby effecting an unwriukled surface for clear printing.

It is therefore an object of this invention to provide a new and improved duplicating device.

It is further an object of this invention to provide an improved means for holding a muslin material tautly and firmly against the arcuate platen portion of my duplieating device.

*It is still further an object of this invention to provide means for adjustably holding a muslin firmly against the arcuate platen portion of my duplicating device.

It is still further an object of this invention to provide means for adjustably holding a muslin firmly against the arcuate platen portion of my printing device wherein the same amount of force is exerted thereby insuring that the muslin is held evenly thereagainst.

Other and further objects of this invention become more readily apparent from reading the specification with the drawing in mind wherein:

FIGURE 1 is a perspective view of my improved duplicating device,

FIGURE 2 is a side elevational view of the platen of my printing device,

FIGURE 3 is a front view of FIGURE 2,

FIGURE 4 is an enlarged view of a portion of FIG- URE 2 showing one end of my movable bar with a thumb nut attached thereto and resting against one of the cam surfaces, and

FIGURE 5 is a sectional view taken along a plane passing through the line 5-5 and looking in the direction of the arrows.

Referring more specifically to the views in the drawing, wherein like characters of reference indicate corresponding parts throughout the views, I have provided a platen lil which consists of a hollow body or casing with an arcnate printing surface 111 at the bottom. The platen has a segmental gear 34 at each end thereof in opposing relationship.

An inverted U-shaped member 12 extends longitudinally from one side of the arcuate printing surface 11. The ink 13 is fed into the platen through an opening at the top of the platen which is covered by the cap 15.

' There are perforations 16 in the arcuate printing surface 11 and absorbent pads 17 which may consist of muslin and silk are held tautly against the arcuate printing surface by a muslin wrapper 18. A plurality of hooks 65 extend from the inverted U-shaped member at different points therealong to support a stencil (not shown) by protruding through apertures therein. The stencil fits over the muslin wrapper 18 and the ink 13 penetrates through the perforations 16 and through the absorbent pads 17 land muslin wrapper 18 to the stencil.

As seen from FIGURE 5, the muslin wrapper is looped at both of its ends and a lock bar 24 is disposed at one end threaded through the loop 18a, while a movable bar 27 is disposed at the other end of the muslin threaded through the loop 18b. A pair of lugs 25 having apertures 25a in straight line alignment extend coextensive with each side of the platen at one end of the platen and the lock bar 24 is removably anchored therein. The movable bar 27 is threaded at each of its ends and it rests within the inverted U-sha-ped member 12 having a bight portion 12a and a pair of sides 12b and 12c. The inverted U-shaped member 12 has a cam suface 31 at each end thereof and the movable bar has spherical thumb nuts 30 re-movably fastened thereto at its threaded ends. Each of the thumb nuts spherical surface rests against the cam surface 31 located proximately with respect thereto. The cam surfaces 31 are shaped to cause the movable bar to move upward in the inverted U-shaped slot an equal amount by turning said thumb nuts an equal amount, thereby causing said muslin wrapper to be pulled tautly and evenly against said arcuate printing surface with equal force at all points of said muslin. As seen in FIG. 5, the bight portion 12a is less than the length of said sides 12b and 12a of the inverted U-shaped member 12.

The segment-a1 gears 34 which are secured to both sides of the platen are positioned to mesh with the racks 35a of the base 35 when the platen is superimposed over the 'base.

In the operation of the device, the paper or card to be printed is placed on the base. The platen is placed on the base so that the gears will mesh with the rack as illustrated in FIGURE 1, and with the stencil being applied to the arcuate printing surface the platen is rocked and the imprinting on the stencil allows ink to flow therethrough to be received on the printing surface of the paper.

By providing the movable bar 27 in combination with the spherical thumb nuts 30 at each end thereof and the cam surfaces 31, I insure that the muslin wrapper is held tautly and evenly against the arcuate printing surface. By moving the spherical thumb nut-s an equal amount in a certain direction the movable bar is moved upwardly an equal amount and accordingly the muslin wrapper is pulled tautly against the arcuate printing surface with an equal amount of force. Also by using spherical thumb nuts, friction is lessened and the movable bar is caused to move with ease upwardly in the inverted U-shaped slot.

Accordingly, when a stencil is placed over the muslin Wrapper and my device has the platen superimposed over the base in a printing position, a clear print is effected because of my improvement.

Having now particularly described and ascertained the nature of my said invention and the manner in which it is to be performed, I declare that what I claim is:

1. In a duplicating device having a printing platen comprising: an arcuate printing surface with openings for ink to flow therethrough, a muslin wrapper positioned to be tautly held against said arcuate surface of said platen to absorb ink therefrom, a lock bar being associated with one end of said muslin wrapper, a movable bar being associated with the other end of said muslin Wrapper, said lock bar being anchored and disposed on one side of said printing platen, said movable bar being associated with said printing platen on the other side of said aircuate surface and extending longitudinally of said arcuate surface, a spherical thumb nut associated with each side of said movable bar and mounted for longitudinal movement along the bar with respect to the arcuate printing surface, and an inverted U-shaped member comprising two sides and a bight portion and extending from one side of said ancuate printing surface, said U-shaped member extending longitudinally with respect to said a-rcuate printing surface and having inclined cam surfaces at each end thereof so that the length of said bight portion of said inverted U-shaped member is less than the length of said side portions, said inclined cam surfaces being disposed to cooperate with the spherical portions of said thumb nuts to cause said movable bar to move upwardly in said inverted U-shaped member and pull said muslin wrapper with equal force at all points thereof when said thumb nuts are moved an equal amount toward each other.

2. A duplicating device, as defined in claim 1, wherein said printing platen has segmental gears at each side thereof and a base having racks at each side thereof, said segmental gears being adapted to mesh with said racks upon superimposing said platen on said base.

References Cited by the Examiner UNITED STATES PATENTS 5/1911 Vandercook 1=01269 9/1929 Kings 101-425 X 

1. IN A DUPLICATING DEVICE HAVING A PRINTING PLATEN COMPRISING: AN ARCUATE PRINTING SURFACE WITH OPENINGS FOR INK TO FLOW THERETHROUGH, A MUSLIN WRAPPER POSITIONED TO BE TAUTLY HELD AGAINST SAID ARCUATE SURFACE OF SAID PLATEN TO ABSORB INK THEREFROM, A LOCK BAR BEING ASSOCIATED WITH ONE END OF SAID MUSLIN WRAPPER, A MOVABLE BAR BEING ASSOCIATED WITH THE OTHER END OF SAID MUSLIN WRAPPER, SAID LOCK BAR BEING ANCHORED AND DISPOSED ON ONE SIDE OF SAID PRINTING PLATEN, SAID MOVABLE BAR BEING ASSOCIATED WITH SAID PRINTING PLATEN ON THE OTHER SIDE OF SAID ARCUATE SURFACE AND EXTENDING LONGIUTDINALLY OF SAID ARCUATE SURFACE, A SPHERICAL THUMB NUT ASSOCIATED WITH EACH SIDE OF SAID MOVABLE BAR AND MOUNTED FOR LONGITUDINAL MOVEMENT ALONG THE BAR WITH RESPECT TO THE ARCUATE PRINTING SURFACE, AND AN INVERTED U-SHAPED MEMBER COM- 